1. Field
The invention is in the fields of methods and compositions for treating earth surfaces, such as dirt and gravel roads and parking lots, to reduce dust from and erosion of such surfaces.
2. State of the Art
Dust control on exposed earth surfaces is a continuing problem. Surfaces such as dirt roads and dirt parking lots generate substantial dust when driven over by a vehicle and can generate dust in windy weather condition. Erosion from vehicle use and from weather conditions, such as rain, snow, or wind, also are problems for such surfaces. Surfaces such as construction sites and tailing disposal sites have similar problems, particularly in windy conditions.
There are various prior art ways of dealing with the dust problems. One way is to spray water and is labor intensive as the surface has to be maintained in a damp condition and damp surfaces dry quickly in many areas.
In some instances, petroleum products, such as diesel fuel, have been used to spread on earth surfaces to reduce dust and erosion. However, such products have been found to cause contamination of water supplies so is now outlawed in most areas. Chemicals such as magnesium chloride, re-claimed asphaltic materials, resins, lignins, lignin sulfonates, lecithin and its derivatives, and various other materials have and are being used in various circumstances, but have associated problems of contamination, only short term effectiveness because it is washed away with rain or is worn away.
Vegetable oil has been tried but has similar problems to other prior art materials in that it is easily washed away by water so is effective after application only until the next rain.
According to the invention, it has been found that an emulsion or semi-emulsion of a fatty acid containing grease or oil, referred to herein as a fatty acid containing material, such as rendered grease and/or used vegetable oil, with water creates a long lasting and cost effective material to apply to earth surfaces to reduce dust from and erosion of such surfaces. It has been found that such product appears to bind to and penetrate into the top layer of earth forming the surface and binds the particles forming the surface and top layer together to form a dust resistant and water repellent, relatively hard surface that appears to last indefinitely.
The fatty acid containing material is mixed with water, with at least one of the ingredients, preferably the fatty acid containing material, at an elevated temperature, so that upon mixing, an emulsion or semi-emulsion product is formed. The product needs to remain in the emulsion or semi-emulsion state only until the product is applied to the surface to be treated. The mixing of the product can take place in advance of application and kept in a tank or drum, or can take place in a tank such as the tank of a truck which applies the material with a spray bar, or may be mixed as the ingredients are pumped together from separate tanks for application through a spray bar or nozzle. If desired, an emulsifying agent may be added. Such agent is generally mixed with the water prior to mixing with the fatty acid containing material. Use of the emulsifying agent appears to allow a lower fatty acid containing material to water ratio and more uniform spreading of the product on an earth surface.
The fatty acid containing material may come from various sources. Used vegetable oil may come from sources such as fast food outlets where it has been used for cooking food such as french fries or from industries such as potato chip or other snack food factories. The rendered grease will generally come from an animal rendering plant, and may be tallow or similar products. The presently preferred fatty acid containing material is a mixture of used vegetable oil and animal fat available from animal rendering plants and referred to as Yellow Grease. Most animal rendering plants collect used vegetable oil, mix it with animal fat to create the Yellow Grease which is used on or as animal feed. The fatty acid containing material may be mixed with water to comprise between about 10% to about 85% of the emulsified or semi-emulsified product, and preferably from about 20% to about 50% of the emulsified or semi-emulsified product. If an emulsifying agent is used, such agent may make up to about 1% of the emulsion or semi-emulsion. The fatty acid containing material is preferably heated prior to mixing with the water with a temperature between about 130xc2x0 F. to about 215xc2x0 F. being satisfactory. The water preferably is also heated, but may be used at ambient temperature.
The emulsion or semi-emulsion may be sprayed onto the surface or poured onto the surface and is absorbed into the surface where it has been found to bind surface particles to form a relatively hard surface thereby reducing dust and erosion of the surface.